Ultrafast Dynamics of Antiferromagnets

With the increasing global demand for high-speed and energy-efficient computing, conventional electronic and magnetic devices are nearing their fundamental performance limits. Although discovered in the 1930s, antiferromagnets were long overlooked in favour of ferromagnets. However, the intrinsic properties of antiferro- magnets make them particularly well suited to meet the performance and scalability requirements of next-generation magnetic technologies. The ultrafast timescales of antiferromagnets are particularly attractive for future memory and logic devices that must operate at speeds beyond the capabilities of conventional ferromagnetic devices. In a broader context, antiferromagnets have the potential to overcome bottlenecks in modern computing architectures by enabling higher data throughput, lower latency and improved energy efficiency. Atomistic modelling is a vital tool to capture the ultrafast dynamics observed within antiferromagnets, offering valuable insights into the fundamental mechanisms driving their responses to external stimuli. This approach significantly enhances our understanding of complex antiferromagnetic systems and phenomena that are often difficult to study experimentally. In this thesis, I present a detailed investigation into the dynamics of antiferromagnetic MnPt to a spin-orbit torque, with the dynamics compared to those of ferromagnetic and ferrimagnetic MnPt. Iridium Manganese (IrMn) is then modelled, and the three antiferromagnetic phases are simulated under an ultrafast laser pulse. Polygranular disordered IrMn is then coupled with a ferromagnetic layer to investigate an alternative method of setting the exchange bias. Subsequently, disordered IrMn is coupled with a ferrimagnetic layer to explore how the exchange bias can be controlled and manipulated. This work provides a comprehensive understanding of the ultrafast dynamics and coupling behaviour of antiferromagnets, relevant as antiferromagnets transition from passive to active elements in the next generation of spintronic devices.